Substituted phthalocyanines



Patented Apr. 21, 1942 UNITED STATES PATENT OFFICE- I suasrl'm'rm238W..." CYANINES Norman Hulton Haddock, Blacklcy, Manchester,

England, alilnor to Imperial tries Limited, a corporation of GreatBritain No Drawing. Application May 17, 1940, Serial- No. 335,871. InGreat Britain May 25, 1939 Claims.

The present invention relates to particular processes for makingtetra-aminophthalocyanines.

It is known that from tetra-(Q-acylaminophthalocyanines oi the benzeneseries the acyl radicals are removed on treatment with, for example,sulphuric acid of about 95%; the resulting amino-phthalocyanines yieldwith acids blue salts the colour of which becomes dull green when theyare treated with alkali. It is also known that theseamino-phthalocyanines can be diazotised by suspending them in acidmedium and treating them in the usual way with sodium nitrite.

This invention relates to the manufacture of metal-free and metallictetra- (4) and tetra-(3) aminophthalocyanines. It is an object of thepresent invention to provide tetra-amino phthalocyanines, as definedbelow, by reduction of the corresponding tetranitro phthalocyanines.

According to the invention'I make the said tetra-aminophthalocyanines byreducing the corresponding tetra-nitrophthalocyanines by the reducingagents specified below. There may be employed, for instance, coppertetra-4-nitroor -tetra-3-nitro-phthalocyanine. M i x t u r e s ofphthalocyanines may also beutilised, for example, a mixture of coppertetra- (4) -nltro and -tetra-(3) -nitrophthalocyanines. Other metallictetra-nitrophthalocyanines, for instance, those of cobalt, nickel,aluminium, lead or magnesium, may also be used. Metallictetra-nitrophthalocyanines are conveniently made, for example, from acompound of the desired metal or the metal itself, together with theappropriate nitrophthalo-dinitrile or riitro-phthalic anhydride,

in conjunction with urea.. Metal-free tetra-nitrophthalocyanines whichmay be made by heating the requisite nitro-phthalodinitrile'with calciumoxide, are likewise useful as starting materials.

Many substances have been applied as agents for the purpose of reducingorganic compounds. A considerable number of these reducing agents may besaid to be largely equivalent inasmuch as one is often capable of takingthe place oi another with similar or nearly the same effect. I have nowfound unexpectedly that whereas the majority of the known reducingagents are useless for the purpose of the present invention, owing tofailure to reduce at all or to do more than effect a partial reduction,or are otherwise unsatisfactory, some reducing agents are able,

not only readily to reduce tetra-nitrophthalocyanines aiiordingtetra-aminophthalocyanines,

' yield 0! diazo-phthalocyanine is relatively low.

but to do so in such a way that the reduction of the four nitro groupsproceeds smoothly and without side-reactions. The reducing agents whichare used in this invention are those of the alkali sulphide class, inwhich expression are included sodium sulphide, sodium hydrogen sulphideand sodium, disulphide. Stannous chloride and sodium hydrosulphite(sodium hyposulphitel are also used as reducing agents according to theinvention. By this means there are obtained in good yieldtetra-aminophthalocyanines. These compounds are green in colour andinsoluble in water. They are turned blue by the action of acids, forexample, hydrochloric acid, seemingly owing to salt-formation.

Tetra-aminophthalocyanines are readily diazotised and are useful asintermediates, namely, diazocomponents, in the preparation of colouringmatters.

The diazotisation of tetra-aminophthalocyanines which have been madefrom tetra-nitrophthalocyanines by the above reduction process,constitutes part of the present invention. The invention includes alsothe precipitation of the tetra-diazo compounds in a form suitable fortechnical handling, and so in solid state, by adding to the solutionsthereof, zinc chloride, cadmium chloride or other salt suitable for theproduction of double salts, or of naphthalene or other sulphonic acidswhich will give sulphonic acid salts of the tetra-diazo compoundssparingly enough soluble in water to be precipitated.

It has been proposed to make tetra-aminophthalocyanines fromaminophthalic acid derivatives. Thus what appears to be coppertetraaminophthalocyanine can be made by heating aminophthalimide withurea and cuprous chloride. Such products however cannot be diazotised.Tetra-aminophthalocyanines obtained by de-acylatingtetra-acylaminophthalocyanines may be diazotiscd, as already mentioned,but owing to gross decomposition of the phthalocyanine molecule havingoccurred during deacylation the By working according to the presentinvention, tetra-aminophthalocyanines may be obtained and diazotised inexcellent yield.

The invention is illustrated but not limited by the following examples,in which the parts are by weight.

Example 1 I parts of copper tetra-(4)-nitrophthalocyanine (made fromi-nitrophthalimide) in the form of an aqueous paste is mixed with 1400parts of water, 200 parts of 33% aqueous sodium hydroxide and 150 partsof sodium hydrosul phite. The mixture is stirred and heated at 50-55 C.for 1 hour. The blue suspension becomes bright green. The mixture isfiltered. The filter cake is stirred with 1000 parts of boiling 20%sodium chloride solution, filtered, washed with cold 10% sodium chloridesolution and dried. There is thus obtained a dark green pulverulentsolid which dissolves in concentrated sulphuric acid to give a brightyellowish green solution. It is almost insoluble in high boiling organicsolvents. When stirred into dilute aqueous mineral acids the colourchanges to blue seemingly by salt formation although the substance doesnot dissolve. When this blue substance is treated with aqueous sodium byhydroxide, the colour changes back to green.

When the same quantity of copper tetra-3-nitro-phthalocyanlne (made from3-nitro-phthalic anhydride) is used instead of copper tetra-4-aminophthalocyanine, copper tetra-3-aminophthalocyanine is obtained. Itis similar in appearance and chemical properties to the product obtainedin the first part of this example.

Example 2 .aqueous sodium hydrogen sulphide solution are added at such arate that the temperature of the mixture does not exceed 25 C. After 20hours, the dark green suspension is diluted with.

70 parts of 10% sodiumsulphite solution. The product is filtered off,washed with 5% aqueous sodium sulphite and then with water. It may nowbe dried to a green powder or conveniently the wet filter-cake may beused for a subsequent chemical operation, e. g. diazotisation.

The purity of the copper tetra-4-aminophthalocyanine so-obtained isabout 96% when assessed in the following manner. 3.25 parts of coppertetra-4-aminophthalocyanine as a aqueous paste are mixed with 3 parts byvolume of 10% aqueous sodium nitrite solution and introduced into theclosed limb of a Lunge nitrometer. 30 parts by volume, of concentratedhydrochloric acid are added and the mixture shaken. A solution of cuprouchloride in hydrochloric acid is introduced. Ferrous sulphate solution iadded to absorb the excess of nitrous gases. Thetetraaminophthalocyanine that was present is calculated from theresidual volume of nitrogen.

Example 3 10 parts of copper tetra-(4)-nitrophthalocyanine in the formof a finely milled aqueous paste are stirred with 200 parts of 33%aqueous hydrochloric acid .till a smooth paste is formed. The suspensionis cooled to 5 C. and 50 parts of crystalline stannous chloride addedgradually so that the temperature of the mixture does not exceed 10 C.The reduction is complete when a test portion added to water gives aviolet coloured precipitate which rapidly change to bright blue whenexposed toair. After dilution with an equal volume of water the productis then filtered on and sucked as dry as possible on the filterf Thefilter cake is made into a paste with 200 parts of a 16% sodiumhydroxide solution and the mixture boiled for 5 minutes after which itis filtered hot. This process is repeated until the product is free fromtin and finally, the copper tetra-4-aminophthalocyanine, so obtained. is

washed with water until free from inorganic matter and dried. The purityof this material is found to be 98% by the method of Example 2. It isgreen in colour and becomes blue on treatment with sulphuric acid.

Copper tetra-(4)-aminophthalocyanine is diazotized as follows. 30 partsthereof as a finely milled aqueous paste are stirred with parts ofsodium nitrite and in all 500 parts of cold water. To this mixture (atbelow 10 C.) is quickly added with stirring 500 parts of 33% aqueoushydrochloric acid. After afew minutes stirring a clear deep greensolution of the tetradiazo com pound is obtained.

The same result is obtained when the suspension of tetra-amino'compoundin aqueous sodium nitrite is added to the aqueous hydrochloric acid.

Example 4 10 parts of copper tetra-(4) -nitrophthalocyanine in the formof a finely milled 10% aqueous paste are stirred in a vessel immersed ina bath of cold water, and 24 parts of crystalline sodium sulphide,dissolved in the minimum quantity of water, added slowly so that thetemperature does not exceed 20 C. After stirring for 20 hours parts of10% sodium sulphite solution are added. The dark green product isfiltered off, washed well with water and dried.

Instead of 24 parts of crystalline sodium sulphide, 21 parts of 27%sodium disulphide solution may be used.

The zinc chloride double salt of copper tetra-(4)diazonium-phthalocyanine chloride is made as follows. 12.3 parts offinely divided copper tetra- (4)-aminophthalocyanine in the form of anaqueous paste are mixed with parts of water and 6 parts of sodiumnitrite. This mixture, cooled to 5 C., is then added to 90 parts ofconcentrated aqueous hydrochloric acid (sp. gr. 1.16) previously cooledto 0 C. To the clear dark green solution of diazo compound thus obtainedthere is added a solution of 25 parts of zinc chloride in 50 parts of0.5% aqueous hydrochloric J acid. There is formed a dark green finelydivided 64 parts of cobalt tetra-(4)-nitrophthalocyanine in the form ofa finely milled 10% queous paste are stirred in an ice-bath and 224 artsof 30% sodium hydrogen sulphide solution added at such a rate that thetemperature of the mixture does not exceed 25 C. After stirring for 20hours, 300 parts of 10% sodium sulphite solution are added. The darkgreen suspension is filtered and the filter cake washed with 5% sodiumsulphite solution and then with water. After drying it is a dark greensolid which when added to 2N-hydrochloric acid changes in colour fromgreen to bluish violet. The purity of this material is about'92% Whennickel tetra-4-nitrophthalocyanine is reduced as described above, nickeltetra-4-aminophthalocyanine is obtained. It is a dark green substancewhich becomes blue when treated with 2N-hydrochloric acid.

Example 6 30 parts of metal-free tetra-(4)-nitrophtha1ocyanine (made byheating 4-nitrophthalonitrile with quick lime) in the form of a finelymilled 10% aqueous paste are stirred in an ice-bath and 145 parts 01 30%sodium hydrogen sulphide solution added at such a rate that thetemperature of the mixtures does not exceed 20 C. After stirring for 20hours 220 parts of 10% sodium sulphite solution are added. Thesuspension is filtered, the filter cake washed with 5% sodium sulphitesolution and then with water and dried. The soobtained product is a darkgreen powder which gives a blue suspension when stirred with 2N-hydrochloric acid.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myseli to speciiic embodiments except asdefined in the ap pended claims.

I claim:

1. A process for the manufacture of tetraamino derivatives orphthalocyanine compounds selected from the group consisting ofmetal-free and metallic phthalocyanines, which comprises subjecting thecorresponding tetranitro phthalocyanine compounds to reduction by meansof a reducing agent selected from the group consisting of stannouschloride, sodium hydrosulfite, and the alkali sulfide class.

2. A process for the manufacture of tetraminocopper-phthalocyanine,which comprises reducing tetranitro-copper-phthalocyanine in aqueousmedium by the aid of a reducing agent of the alkali sulfide class.

3. A process for the manufacture of tetraminocopper-phthalocyanine,which comprises reducing tetra-nitro-copper-phthalocyanine in alkalineaqueous medium by the aid of an alkaline hydrosulfite.

4. A process for the manufacture of tetraminocopper-phthalocyanine,which comprises reducing tetranitro-copper-phthalocyanine in acidaqueous medium by the aid of stannous chloride.

5. A process for the manufacture of tetraamino derivatives ofphthalocyanine compounds selected from the group consisting ofmetal-free and metallic phthalocyanines, which comprises subjecting thecorresponding tetranitro phthalocyanine compounds to, reduction inaqueous medium by the aid of sodium hydrogen sulfide.

NORMAN HULTON HADDOCK.

